avoid using sql.Row.Append() (#3154)

Author: jycor

sql/rowexec/dml_iters.go

@@ -754,7 +754,8 @@ func (u *updateSourceIter) Next(ctx *sql.Context) (sql.Row, error) {
 		newRow = newRow[len(newRow)-expectedSchemaLen:]
 	}
 
-	return oldRow.Append(newRow), nil
+	row := append(oldRow, newRow...)
+	return row, nil
 }
 
 func (u *updateSourceIter) Close(ctx *sql.Context) error {

sql/rowexec/insert.go

@@ -233,13 +233,11 @@ func (i *insertIter) handleOnDuplicateKeyUpdate(ctx *sql.Context, oldRow, newRow
 				if !ok {
 					return nil, err
 				}
-
 				val = convertDataAndWarn(ctx, i.schema, newRow, idx, err)
 			} else {
 				return nil, err
 			}
 		}
-
 		updateAcc = val.(sql.Row)
 	}
 	// project LHS only